The Second LHAASO Collaboration Conference in 2026 & The Academic Symposium for the 10th Anniversary of the LHAASO collaboration

The energy reconstruction of LHAASO-KM2A relies on the electron and muon content of extensive air showers and is therefore sensitive to the hadronic interaction model. We compare proton- and iron-induced showers simulated with CORSIKA 7.4010/EPOS-LHC and CORSIKA 7.8050/EPOS-LHC-R in the energy range 100 TeV–100 PeV, matched in primary energy and zenith angle and analysed with a KM2A-like particle selection.

Compared with the EPOS-LHC configuration, the EPOS-LHC-R configuration predicts 2–6% fewer electrons on average, with a reduction of up to 13% for protons at 100 PeV, while the muon content increases by approximately 9% for iron and 3% for protons. These differences correspond to estimated energy-scale shifts ranging from +12% for iron at 100 TeV to −12% for protons at 100 PeV. These energy- and composition-dependent shifts affect both the normalization and the shape of the reconstructed cosmic-ray spectra. For a power-law spectrum with a spectral index of 2.7, a uniform 12% energy-scale shift corresponds to a flux change of approximately 20%. Our results quantify the sensitivity of KM2A energy reconstruction to the simulation configuration and provide an estimate of the resulting systematic uncertainty in the all-particle and light-component cosmic-ray spectra.